fix: address structured context final-review findings

src/wf_core/runtime/ops/flow.py

@@ -5,6 +5,7 @@ from typing import Any
 from wf_core.errors import WorkflowExecutionError
 from wf_core.models.workflow import Workflow
 from wf_core.run_state import (
+    ROOT_FRAME_ID,
     ExecutionFrame,
     FrameStatus,
     RunState,
@@ -12,6 +13,7 @@ from wf_core.run_state import (
     StepExecutionResult,
     TraceEntry,
 )
+from wf_core.runtime.ops.frames import frame_context_view
 from wf_core.runtime.ops.schemas import validate_payload_against_schema
 from wf_core.runtime.ops.state import project_output
 from wf_core.runtime.scheduler import (
@@ -163,9 +165,6 @@ def finalize_run(workflow: Workflow, run: RunState) -> RunState:
         run.outcome = "ok"
     # Root workflow output keeps standard root facts consistent by projecting
     # against the root frame's derived context rather than an empty mapping.
-    from wf_core.run_state import ROOT_FRAME_ID
-    from wf_core.runtime.ops.frames import frame_context_view
-
     root_frame = run.frames.get(ROOT_FRAME_ID)
     root_context: dict[str, Any] = (
         dict(frame_context_view(run, root_frame).graph)

src/wf_core/runtime/scheduler.py

@@ -74,7 +74,9 @@ class ForeachIterationMetadata:
             raise WorkflowExecutionError(
                 f"malformed foreach activation id for frame {frame.id!r}"
             )
-        if not isinstance(loop_index, int):
+        # `bool` is an `int` subclass; an index of True/False is corrupt
+        # persisted metadata, not item 1/0.
+        if not isinstance(loop_index, int) or isinstance(loop_index, bool):
             raise WorkflowExecutionError(
                 f"malformed foreach loop index for frame {frame.id!r}"
             )